System for treating, in particular, cataphoretically immersion painting vehicle bodies

ABSTRACT

In a system for treating, in particular, cataphoretically immersion painting objects, the objects ( 4 ) to be treated pass through at least one bath ( 100 ) and a drip zone ( 101 ) located down from this bath ( 100 ) before being introduced into a dryer ( 105 ). The objects ( 4 ) are each moved by a conventional trolley ( 5 ) comprising a traveling mechanism that can travel along the movement path of the objects ( 4 ). This trolley also comprises at least one pivotal arm ( 50, 51 ) that is coupled to the traveling mechanism, and has a holding device ( 61 ) that is coupled in an end area of the pivotal arm ( 50, 51 ) and provided for holding the object ( 4 ). Like the pivotal movement of the pivotal arm ( 50, 51 ) and the pivotal movement of the holding device, the linear movement of this trolley ( 5 ) can also be independently controlled. The trolley ( 5 ) not only guides the objects ( 4 ) through the bath ( 100 ) but also through the drip zone ( 101 ). In the drip zone, the trolley ( 5 ) simultaneously serves as tilting device with which the objects ( 4 ) can be tilted into an angular position with regard to the horizontal, said angular position enabling the bath liquid to drip off. This eliminates the need for a separate tilting device as required in the prior art whereby simultaneously enabling the liquid to completely drip off of the objects ( 4 ) and thus preventing, to the greatest possible extent, the formation of fat edges that would have to be removed by grinding upon completion of the drying process effected inside the dryer ( 105 ).

The invention relates to a system for treating, in particular forcataphoretically dip-coating, articles, in particular vehicle bodies,comprising

-   -   a) at least one bath, in which a treatment liquid is situated,        into which the articles are to be dipped;    -   b) a feed device, by means of which the articles are conveyed        through the system and in the process are dipped into the at        least one bath;    -   c) a dripping zone, which is disposed in the direction of motion        downstream of the last bath;    -   d) a tilting apparatus within the dripping zone, in which        apparatus the articles may be tilted into an angular position        relative to the horizontal that is suitable for dripping-off;    -   e) a drier situated downstream of the dripping zone.

Vehicle bodies or other articles leaving the last rinsing bath or thelast spraying zone of a cataphoretic dip-coating system have to drip offwell prior to entry into the drier, wherein at the same timeflashing-off occurs. In said case, it is necessary to avoid theformation on the articles of fat edges, so-called “runs”, which afterdrying in the downstream drier are removable only by laborious grindingoperations. In known systems of the initially described type, the feeddevice is changed downstream of the last bath of the cataphoreticdip-coating zone. For example, the vehicle bodies, which are conveyedwith the aid of a shuttle conveyor through the various baths and arethemselves carried by skids, are deposited in the dripping zone onto aroller conveyor. This roller conveyor, because of the extremelycontaminating effect of the liquid entrained from the bath, has to bemade substantially of special steel.

To enable efficient draining of the liquid off the vehicle bodies and inparticular out of their cavities, in the known coating systems aseparate tilting apparatus is provided within the dripping zone. Thevehicle bodies have to be transferred from the roller conveyor onto thistilting apparatus, where they are brought into a tilted positionrelative to the horizontal, then swivelled back into the horizontal andtransferred back to the roller conveyor system. The equipment outlay forthis is high. Furthermore, given a fast cycle time of the coatingsystem, the respective vehicle body situated in the tilting apparatusmay be swivelled out of the horizontal for dripping-off only for arelatively short time. In many cases, therefore, the dripping-offoperation may not be completed inside the tilting apparatus, the resultbeing that fat edges may form on the surfaces of the vehicle body.

A further drawback of the known system is that with the aid of thetilting apparatus generally only a single angular position of thevehicle body relative to the horizontal may be achieved. It is howeveroften not guaranteed that in this single angular position the entrainedliquid may reliably run out of all of the cavities of the vehicle body.

The object of the present invention is to develop a system of theinitially described type in such a way that it involves only a lowequipment outlay and yet achieves a better result in the dripping zone.

This object is achieved according to the invention in that

-   -   f) the feed device comprises at least one feed carriage, which        in turn comprises:        -   fa) running gear movable along the path of motion of the            articles;        -   fb) at least one swivel arm coupled to the running gear;        -   fc) a holding device coupled to the swivel arm for at least            one article;        -   fd) mutually independently actuable drives for the            translational movement, the swivelling motion of the at            least one swivel arm and of the holding device;    -   g) the at least one feed carriage simultaneously serves as a        tilting apparatus and for said purpose is movable over the        dripping zone to a point in the vicinity of the drier.

The feed carriage utilized by the present invention is known inprinciple from DE-U-201 05 676. There, however, it is used only fordipping the articles to be treated into and out of a bath. The presentinvention recognizes that this feed carriage, owing to its style ofconstruction, is suitable not only as an apparatus for dipping articlesinto and out of baths but also as a tilting apparatus in the drippingzone owing to the possibility of bringing the fed articles into anydesired angular position. The running surfaces, along which the feedcarriage travels, therefore need merely be extended beyond the zone ofthe treatment baths and across the dripping zone. A transfer of thearticles onto a separate feed device within the dripping zone istherefore unnecessary, as is locking on a separate tilting apparatus andunlocking for further conveying, as was required in the background art.

In contrast to the background art, with the present inventiondripping-off in a tilted position relative to the horizontal may occuralso while the feed carriage is moving. The dripping-off time maytherefore be extended compared to the dripping-off time in knownsystems. If different articles are treated in succession, the angularposition relative to the horizontal that is suitable for dripping-offmay be selected for each article.

A further big advantage of the use of such feed carriages is that bymeans of a suitable inclination of the vehicle bodies already over thelast bath a very extensive dripping-off may be achieved and, for thisreason alone, the entrainment of bath liquid is substantially reducedcompared to the background art. On the whole, with the system accordingto the invention, dripping-off may be completed in an optimum mannerbefore the articles enter the drier, thereby substantially avoiding theformation of fat edges, which would necessitate laboriousafter-treatment.

Particularly preferred is the embodiment of the invention, in which theat least one feed carriage is controllable in such a way that itsholding device is brought within the dripping zone into at least twopositions, in which it is tilted differently relative to the horizontal.This development takes account of the experience that for articles of acomplicated shape containing cavities it is often impossible to find a(single) angular position relative to the horizontal that allowsefficient draining and/or dripping of the liquid from all points andfrom all cavities.

There now follows a detailed description of an embodiment of theinvention with reference to the drawings; the drawings show:

FIG. 1: a side view of a feed carriage, which is used in the coatingsystem, with a vehicle body fastened thereto in normal feed position;

FIG. 2: a side view of the feed carriage similar to FIG. 1, in whichhowever the vehicle body is swivelled out of the feed position;

FIG. 3: the plan view of the feed carriage of FIG. 2;

FIG. 4: a perspective view of the feed carriage plus vehicle body ofFIG. 1;

FIG. 5: a section through FIG. 3 according to the line VIII-VIII of FIG.3;

FIGS. 6 and 7: enlarged detail views of the feed carriage in the regionof the wheels positioned on running surfaces;

FIG. 8: a diagrammatic view of the transition region of the coatingsystem between the last spraying/immersion container and thecataphoretic dip-coating drier.

First, there now follows a detailed description with reference to FIGS.1 to 7 of the style of construction of feed carriages 5 of the type usedin the coating system illustrated in the further drawings. Such feedcarriages 5 are admittedly known in principle from DE-U-201 05 676, towhich reference is additionally made. However, since a knowledge of thekinematics of these feed carriages 5 is a prerequisite to anunderstanding of the overall system, the explanation of the feedcarriages 5 is repeated to the necessary extent in the presentdescription.

As FIGS. 3 and 4 in particular reveal, each feed carriage 5 has twolongitudinal tie-bars 7, 8, at the underside of each of which two twinwheels 9, 10 and 11, 12 are mounted rotatably about a horizontal axis.The wheels 9 to 12 are additionally rotatable in each case with the aidof a not specifically illustrated swivelling bolster about a verticalaxis, with the result that the alignment of the twin wheels 9 to 12relative to the respective longitudinal tie-bars 7, 8 may be varied.

The twin wheels 9, 10 roll along a first running surface 13 and the twinwheels 11, 12 roll along a second running surface 14 parallel to thefirst. The running surfaces 13, 14 are in turn mounted in each case onan I-beam 15, 16, which is supported by a non-illustrated steelstructure.

In the middle of the, in FIGS. 3 and 4 right, second running surface 14a guide rib 17 is provided, over which guide elements 18 having acomplementary recess (cf. FIG. 7) engage. In each case one guide element18 is connected to the swivelling bolster of an associated twin wheel 11and/or 12 in such a way that it rotates this twin wheel 11 and/or 12about the vertical axis in accordance with the course of the guide rib17. The twin wheels 11, 12 therefore follow the running surface 14. Thetwin wheels 9, 10 associated with the first, in FIGS. 3 and 4 leftrunning surface 13, on the other hand, are designed purely as trailingwheels; in other words, no separate guide means are provided forinfluencing the angular position of the wheels about their vertical axisof rotation. In this way, the standards of accuracy demanded of theguide means that hold the feed carriages 5 on the running surfaces 13,14 may be kept low.

Vehicle bodies 4 are carried on the feed carriages 5 with the aid of animmersion apparatus, which comprises one swivelling apparatus on eachside of the vehicle bodies 4. Each of these swivelling apparatuses has aswivel arm 50, 51, which in a manner yet to be described may swivel in avertical plane extending parallel to the feed direction.

For this purpose, each swivel arm 50, 51 is connected by a stub shaft52, 53, which extends at right angles to the feed direction, to theoutput shaft of a gear unit 54, 55. The gear unit 54, 55 is fastened tothe respective longitudinal tie-bar 7, 8 of the feed carriage 5approximately in the central region thereof. It is driven by a motor 56and/or 57, which is flange-mounted laterally on the gear unit 54, 55.

The, in direction of motion, rear ends of the swivel arms 50, 51 arehinge-connected to a link 58, 59, which in the normal feed positionshown in FIG. 1 extends vertically downwards from the correspondingswivel arm 50, 51. The bottom ends of the links 58, 59 are connected toone another by a transverse tie-bar 60, which extends at right angles tothe direction of motion and is in turn connected rigidly to the centralregion of a support platform 61 for the vehicle body 4. The direction ofextension of the two links 58, 59 in said case runs at right angles tothe plane of the support platform 61.

The angular position that the links 58, 59 occupy relative to the swivelarms 50, 51 is determined in each case by an adjusting device, which asa whole bears the reference character 62 and/or 63. Each of theseadjusting devices 62, 63 comprises a linkage having two parallel pushrods 64, 65 and/or 66, 67, which at their opposite ends are connected toone another in each case by a connecting strap 68, 69 and/or 70, 71.The, in direction of motion, rear connecting straps 69 and/or 71 arefastened at their bottom end rigidly to the transverse tie-rod 60.

The, in direction of motion, front connecting straps 70, 71, on theother hand, are each connected rigidly to a stub shaft, which is notvisible in the drawings because it extends coaxially through theassociated stub shaft 52, 53 designed as a hollow shaft. These furtherstub shafts extend also through the gear units 54, 55 and are coupled tothe output shafts of further gear units 78, 79, which are fastenedlaterally to the gear units 54, 55. Drive motors 80, 81 are alsoflange-mounted laterally onto the gear units 78, 79.

The front ends of the two swivel arms 50, 51 jointly carry acounterweight 88, so that the torques acting upon the stub shafts 52, 53are approximately counterbalanced when a vehicle body 4 is placed on.

The twin wheels 19 to 12 of the feed carriages 5 are not themselvesdriven. Rather, forward propulsion of the feed carriages 5 is effectedby means of a separate drive, which is described in detail below withreference to FIGS. 3 to 7.

Extending parallel to the two running surfaces 13, 14 are two verticallyaligned, stationary driving flanges 26, 27. These interact in each casewith a press roller drive 28, 29, which is fastened to the lateralsurface of the adjacent longitudinal tie-bar 7, 8 by means of a link 30,31. The press roller drives 28, 29 each comprise an electric drive motor32, 33 and a drive gear unit 34, 35. The latter drives the parallel,vertical axles of two press rollers 36, 37 and/or 38, 39, which arepressed from both sides against the respective associated driving flange26 and/or 27. When the drive motors 32, 33 are energized, the pressrollers 36, 37 and/or 38, 39 run along the respective lateral surfacesof the driving flanges 26, 27 and, in so doing, move the feed carriage 5forward along the running surfaces 13, 14.

Each feed carriage 5 comprises its own carriage controller, under theregime of which it executes both its translational movement along therunning surfaces 13, 14 and the swivelling motions of the swivel arms50, 51 and of the support platform 61.

In summary, the movement options of a vehicle body 4 carried on a feedcarriage 5 may be described as follows:

The overall movement arises from a superposition of the lineartranslational movement of the feed carriage 5, a first swivelling motionthat the swivel arms 50, 51 execute relative to the longitudinaltie-bars 7, 8 and is linked to a lifting and/or lowering of the vehiclebody 4, and a second swivelling motion that the vehicle body 4 situatedon the support platform 61 executes relative to the swivel arms 50, 51.All of these types of movement may be carried out completelyindependently of one another, thereby leading to practically any desiredkinematics of the vehicle body 4. In the previously described embodimentof a feed carriage 5, the swivelling motion is transmitted to thesupport platform 61 from the motors 80, 81 by means of linkage-likeadjusting devices 62, 62. Naturally, the adjusting devices may howeverbe designed differently, e.g. they may comprise continuous metal beltsas torque-transmitting elements.

Reference is now made to FIG. 8, which shows the detail of a coatingsystem that is of relevance in the present context. In this drawing, inorder to illustrate the sequence of motion, a vehicle body 4 is shown atdifferent points as well as at different levels and angles relative tothe horizontal. This vehicle body 4 is to be imagined as being carriedby a feed carriage 5. The feed carriage itself is not illustrated forthe sake of clarity. That the vehicle body 4 may occupy the respectivepositions, and how it does so, is however plain from the previousdescription of the feed carriage 5.

The left region of FIG. 8 shows the last treatment stage in the form ofrinsing bath 100 of a cataphoretic dip-coating zone of the coatingsystem, which includes, further to the left and adjoining the portionillustrated in FIG. 8, further rinsing baths and/or spraying zones aswell as a cataphoretic dip-coating bath. The vehicle body 4 moves on thefeed carriage 5 “net” in FIG. 8 from left to right. A “net movement”means that the feed carriage 5 on the whole moves from left to right,although this does not rule out temporary reversals of motion when thisis necessary to achieve specific kinematics of the vehicle body 4. Tocite an example: if a vehicle body 4 is to be lifted substantiallyvertically, the swivel arms 50, 51 of the feed carriage 5 are swivelledin a corresponding manner; the component of motion in horizontaldirection that is linked to this swivelling motion of the vehicle body 4is compensated by a corresponding movement of the feed carriage 5 inhorizontal direction, which may also be counter to the “net feeddirection”.

The rinsing bath 100 of the catalytic dip-coating zone is adjoined by adripping zone 101. The vehicle bodies 4 are moved also through thisdripping zone 101 on the same feed carriage 5 as they travelled onthrough the cataphoretic dip-coating zone. Immediately after removalfrom the rinsing bath 100 the vehicle body 4, by virtue of suitableswivelling of the swivel arms 50, 51 and of the support platform 61, isinclined at such a steep angle that the leading body end points upwardsand the tail of the body points downwards. In this position the liquidcarried out of the rinsing bath 100 by the vehicle body 4 may run outand drip off and be collected in a trough 102 disposed on the floor ofthe dripping zone 101. The vehicle body 4 may be conveyed further inthis “tilted” position by the feed carriage 5; i.e. the movement doesnot have to be interrupted for the dripping-off process.

In the course of travel of the feed carriage 5 through the dripping zone101, the vehicle body 4 after a specific time is swivelled back into itsnormal, horizontal position, as is shown in FIG. 8. This is followed, bymeans of a corresponding movement of the swivel arms 50, 51 and of thesupport platform 61, by a swivelling of the vehicle body 4 in theopposite direction, in which therefore the leading region of the vehiclebody 4 points downwards, while the tail is raised. In this position,entrained liquid from the rinsing bath 100 may run out of cavities, fromwhich the liquid could not escape in the initially adopted tiltedposition. Finally, in the dripping zone 101 the vehicle body 4 isreturned to a horizontal position.

The dripping zone 101 is adjoined by a transfer device 103, the style ofconstruction of which is not relevant in the present context. Thistransfer device 103 removes the vehicle body 4 from the feed carriage 5,which is returned for loading with another vehicle body 4. The transferdevice 103 then places the vehicle body 4 on a lifting apparatus 104 inthe intake lock 105 a of a conventional drier 105, such as is usuallydisposed downstream of the cataphoretic dip-coating zone of a coatingsystem. Once again, the exact style of construction both of the liftingapparatus 104 and of the drier 105 is of no importance in the presentcontext.

1. A system for treating articles, comprising at least one bath, inwhich a treatment liquid is situated, into which the articles are to bedipped; a feed device, which is adapted to convey the articles areconveyed through the system and in the process to dip into the at leastone bath; a dripping zone, which is disposed in direction of motiondownstream of a last bath; a tilting apparatus within the dripping zone,wherein the articles may be tilted into an angular position relative tothe horizontal that is suitable for dripping-off; a drier disposeddownstream of the dripping zone, and, the feed device comprises at leastone feed carriage, which in turn comprises: running gear movable alongthe path of motion of the articles; at least one swivel arm coupled tothe running gear; a holding device coupled to the swivel arm for atleast one article; and mutually independently actuable drives for thetranslational movement, the swivelling motion of the at least one swivelarm and of the holding device; wherein the at least one feed carriagesimultaneously serves as a tilting apparatus and is movable over thedripping zone to a point in the vicinity of the drier.
 2. The system ofclaim 1, wherein the at least one feed carriage is controllable in sucha way that its holding device within the dripping zone is brought intoat least two positions, in which it is tilted differently relative tothe horizontal.